US4522468A - Information display device having a liquid crystal cell - Google Patents

Information display device having a liquid crystal cell Download PDF

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US4522468A
US4522468A US06/047,393 US4739379A US4522468A US 4522468 A US4522468 A US 4522468A US 4739379 A US4739379 A US 4739379A US 4522468 A US4522468 A US 4522468A
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cell
voltage
liquid crystal
analyzer
light
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Michel Goscianski
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US Philips Corp
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US Philips Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/1396—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133531—Polarisers characterised by the arrangement of polariser or analyser axes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/1393—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/01—Number of plates being 1

Definitions

  • the invention relates to an information display device having a cell of nematic liquid crystal between two sets of electrodes, which cell is provided between light-polarising means and light-analysing means, the light transmission through the device being controlled by means of electrical control voltages between the sets of electrodes.
  • the invention also relates to the application of the display device to realize devices for addressing information arranged according to lines and columns.
  • Display devices of this type are known from several publications.
  • several categories of liquid crystals are used in the form of a cell which is formed by a thin layer of liquid crystal of which each surface is provided with a light-pervious electrode so as to apply a variable electrical field parallel to the thickness.
  • layer thickness and cell thickness which means substantially the same.
  • the liquid crystal used is a homeotropic pattern having a negative dielectric anisotropy ( ⁇ .sub. ⁇ ⁇ .sub. ⁇ ).
  • the liquid crystal is uniaxial and the optical axis is parallel to the thickness of the cell when the strength of the applied electrical field is zero.
  • the liquid crystal then exerts no influence on the polarisation state of the light which is incident at right angles. Extinction of the light beam between the polariser and the linear analyser is obtained when the polarisation directions of these two are mutually perpendicular.
  • a linearly polarised incident vibration which is parallel to or perpendicular to the direction of alignment of the molecules at the entrance of the cell follows the rotary movement of the center and rotates through the same angle ⁇ as the molecules of the liquid crystal.
  • the linearly polarised light is transformed into elliptically polarised light. In this case there is light transmission between parallel polarisers.
  • the known display technique of information by means of the cells is based on this phenomena.
  • the light transmission between the polarisers is controlled by means of an information-containing electrical voltage which is applied between the two surfaces of the liquid crystal.
  • the electrical voltage varies between a minimum value and a maximum value.
  • the minimum voltage value corresponds to an optical threshold above which the electrical field is such that the polarisation of the light in the cell varies under the influence of the field, which results in a light transmission variation between the polarisers.
  • a desired property of the devices is the contrast between the transmitted light and the non-transmitted light as a function of the signal amplitude swing or change. The device is better according to whether the contrast is large with small voltage swing or change.
  • a control signal voltage whose minimum value is smaller than or equal to the optical threshold
  • a control signal voltage is used whose minimum value is larger than the threshold and corresponds to induction of birefringence in the liquid crystal and hence to a variation of the polarisation of the light which passes through the cell.
  • the polarisation means which precede the cell and on the other hand the analysing means which succeed the cell are placed in such manner that the light transmission is minimum when the value of the signal voltage is minimum, which above the minimum signal voltage value light transmission becomes larger when the voltage increases.
  • the resulting light transmission curve is a curve which shows a much larger slope dependent on the voltage value of the applied signal.
  • the control of the cell may then be carried out by means of a small signal swing or change, for example, in the order of a few tenths of a volt, while the contrast assumes large values.
  • the information addressing at the crossings of the lines and columns may be effected by means of a large number of lines and with a strong contrast.
  • the invention also permits extinction of the transmitted light at control voltages which are larger than the optical threshold due to the fact that according to the invention transmission is determined by either means for polarising the light at the entrance of the cell, or analysing means of the transmitted light at the output of the cell, or both means simultaneously.
  • the desired results are either a direct compensation of the induced birefringence in the crystal at the minimum value of the signal voltage used, or a variation of the nature of the polarisation of the incident light at the entrance of the cell, or of the nature of the vibration emanating from the cell, the vibration being afterwards easily extinguished by means of a rectilinear analyser.
  • extinction is obtained in a simpler manner by a simple rotation of the rectilinear polarisers and analysers with respect to their usually parallel positions.
  • the measures taken may relate both to operation at normal light incidence on the cell and to an operation with oblique incidence of the light on the cell.
  • the light beams may have parallel rays or diverge slightly.
  • FIG. 1 is a sectional view of a device having a cell with a nematic liquid crystal which is situated between a polariser and an analyser,
  • FIG. 2 shows a light transmission curve of a cell with a nematic liquid crystal as a function of the signal voltage between the electrodes with various mutual orientations of the polariser and the analyser
  • FIG. 3 shows diagrammatically the principle of a first device according to the invention
  • FIG. 4 shows diagrammatically the principle of a second device according to the invention
  • FIG. 5 shows diagrammatically the principle of a third device according to the invention
  • FIG. 6 is a diagrammatic sectional view of a device according to a fourth embodiment of the invention in which obliquely incident light is used.
  • FIG. 7 finally shows diagrammatically the principle for operation of the device according to the fourth embodiment.
  • reference numeral 10 denotes a layer of nematic liquid crystal which is placed between two electrodes 11 and 12 between which an electric voltage V is applied.
  • the assembly formed by 10, 11 and 12 is a so-called nematic cell.
  • a polariser 13 polarizes the light beam 14. It is assumed that the central ray 14' of the beam 14 is incident perpendicularly to the nematic cell.
  • the beam may be oblique to the cell.
  • An analyser 15 receives the light at the output of the cell.
  • FIG. 2 shows in a rectangular system of axes the curves A and B which represent the variations of the light transmission T of the device as a function of the electrical voltage V which is applied between the electrodes when the liquid crystal has a helical pattern and when the polariser and the analyser are linear; the curves A and B are obtained for two different orientations of the polarizers and analysers.
  • the nematic cell is such that in the absence of an electrical field applied to the cell, the direction of alignment of the axis of the molecules rotates through an angle ⁇ /2 from one surface of the cell to the other, the axis, however, remaining parallel to the plane of the electrodes.
  • ox represents the direction of alignment of the molecules at the input of the cell
  • oy denotes the direction of alignment of the molecules at the output of the cell.
  • Curve A corresponds to the prior art according to which the direction of polarisation of the polariser and the analyser is parallel to ox or oy.
  • an optical threshold is achieved which is denoted on curve A by the dot S at which polarisation of light is influenced within the cell and thereafter becomes elliptical.
  • Light is then transmitted between parallel polarisers. Above the point S the light transmission does not at least initially vary considerably in accordance with the supplied voltage.
  • Curve B in FIG. 2 denotes the light transmission which is obtained according to the invention when the polarizers and the analysers are no longer parallel but are each rotated through an angle ⁇ on either side of the direction ox.
  • FIG. 3 shows the positions of the polariser and the analyser according to the directions OP and OA, respectively, in the case of a left helical structure. When the voltage is smaller than V m , the cell, up to the optical threshold, shows a light transmission which is not equal to zero.
  • the light transmission is substantially zero due to the fact that the vibration emanating at the output of the cell is a substantially rectilinear vibration according to the direction OM which forms an angle ⁇ with the direction oy and thus is perpendicular to OA. Above this value the light transmission increases considerably as a function of the applied voltage and with a slope which is much stronger or steeper than the slope when the polariser and the analyser are parallel to ox or oy.
  • the nematic cell used may be a cell in which the rotation of the axis of the molecules from one cell surface to the other differs from the value ⁇ /2.
  • the direction ox denotes the direction of alignment of the molecules at the input of the cell
  • the direction oz which forms an angle ⁇ with ox denotes the direction of alignment of the molecules at the output of the cell when the voltage is zero.
  • the direction OP represents an incident linearly polarized vibration on the input surface which forms an angle ⁇ with the direction ox.
  • the cell has a linear polariser with direction OP and an analyser with direction OA, perpendicular to ON, which forms the angle ⁇ /2- ⁇ with the direction of alignment oz of the molecules at the output of the cell.
  • a light transmission curve is then obtained which is analogous to curve B in FIG. 1.
  • the angle ⁇ ⁇ /2+2 ⁇ .
  • the polariser and the analyser are orientated in the same direction which forms an angle ⁇ with ox or with the perpendicular to ox, as shown in FIG. 5.
  • the direction which is denoted in FIGS. 3, 4 and 5 by the arrows is chosen as a positive direction of rotation.
  • the angle ⁇ is positive for the polariser and is negative for the analyser in the case of a left structure
  • the angle ⁇ is negative for the polariser and is positive for the analyser in the opposite case.
  • the angles ⁇ and ⁇ /2- ⁇ are positive for a left structure but are negative for a right structure
  • the angle ⁇ is positive or negative according as a left structure or a right structure is used.
  • a steep transmission characteristic of the cell is obtained as a function of the applied signal voltage in a different manner.
  • liquid crystal configurations are used of the type which are either homeotropic with a negative dielectric anisotropy ( ⁇ .sub. ⁇ ⁇ .sub. ⁇ ) or are helical ( ⁇ .sub. ⁇ > ⁇ .sub. ⁇ ).
  • the light is polarised linearly at the input of the cell. Under the influence of a signal applied to the electrodes, a birefringence is induced in the liquid crystal so that at the output thereof the light is elliptically polarised.
  • the analysing means used at the output of the cell comprise in the first instant a birefringing phase shifting plate the neutral lines of which are parallel to the neutral lines which are induced in the liquid crystal by the signal voltage of value Vm, the phase shift caused by the phase shifting plate being equal to and showing the same sign as the phase shift which is caused by the liquid crystal.
  • the cell produces at its output a vibration which is linearly polarised.
  • a linear polarizer is provided perpendicular to the vibration which is supplied by the phase shifting plate.
  • phase shifting plate Since the neutral lines of the liquid crystal cell are parallel to the neutral lines of the phase shifting plate, the phase shifts caused by the components are composed algebraically. The sum of the phase shifts is thus independent of the sequence in which the radiation beam passes through the components.
  • the phase shifting plate may be arranged before or behind the liquid crystal cell. According to these two arrangement possibilities a device is obtained for which the light transmission is analogous to the light transmission represented by curve B of FIG. 2, in which the light transmission is zero when the applied signal voltage has the value Vm.
  • the elliptically polarised variation obtained at the output of the cell is converted into a linearly polarised vibration by means of a ⁇ /4 plate of which the neutral lines are parallel to the axes of the elliptically polarized vibration.
  • a linear analyser is arranged perpendicularly to the resulting linearly polarized vibration.
  • a homeotropic configuration it is possible to provide the ⁇ /4 plate between the polariser and the cell.
  • all the above-described devices may be used both for a normal light incidence and for an oblique light incidence.
  • the light beam may also be formed by parallel rays or may be diverging to a certain extent.
  • the invention proposes an embodiment in which the configuration for the liquid crystal is homeotropic.
  • This embodiment is shown diagrammatically in a sectional view of FIG. 6, while the operation thereof is shown in FIG. 7.
  • the sectional view shown in FIG. 6 comprises the electrical field E which is applied to the cell and the direction of the light beam.
  • the liquid homeotropic crystal is referenced 10 and the electrodes are referenced 11 and 12.
  • a voltage Vm is applied between the electrodes.
  • the light is incident obliquely on the cell according to an angle i with respect to the normal 19 to the cell. This direction of incidence is such that the light within the cell is parallel to the direction of the molecules at the value Vm of the voltage applied between the electrodes.
  • the direction is the direction of the refracted light ray 16 corresponding to the incident ray 17.
  • the device comprises the linear polariser 13 and at the output the linear analyser 15.
  • the analyser and polariser are provided in such manner that their directions of polarisation are mutually perpendicular and that the bisectrix of the directions is parallel to the common direction of the rays 17 and 18 at the input and at the output of the cell.
  • the directions of polarisation are shown in FIG. 7 according to a plane which is perpendicular to the rays 17 and 18.
  • ⁇ denotes the direction of the plane formed by the field E and the direction 16
  • the direction of vibration passed by the polariser is denoted by OP
  • the direction of vibration passed by the analyser is denoted by OA.
  • the vibration OP is not influenced by the cell and there is no light transmission whatsoever.
  • a particular structure of these devices is that which enables the display of data according to lines and columns.
  • the n electrodes on each face are realized in agreement with known technology and in the form of two groups of parallel strips. On one surface the direction of the strips differs from that of the strips on the other surface, the strips of one surface, termed lines, being, for example, normal to the strips of the other surface, termed columns.
  • the lines are fed sequentially with a voltage V 1 and simultaneously the columns are fed with a voltage V 2 the positive or negative polarity of which depends on the presence or absence of information at the crossings with the addressed line.
  • the voltages V 1 and V 2 are chosen to be so that the effective voltage V F between the crystal surfaces in the points without information is approximately equal to the value V m on the curve B or the analogous curves which are obtained for other embodiments.
  • the effective voltage V 0 between the crystal surfaces in the points having information is higher than V m . Due to the steep increase of the light transmission of the device as a function of the applied signal, a very good contrast is obtained for a large number of lines, while the difference between V O and V F nevertheless is only a few tenths of a volt.
  • An improvement of the display devices forming part of the invention relates to the addition to such a device of a light diffuser arranged behind the analyser so that it is possible to directly observe visually the information displayed at a large angle.
  • the various cells used in accordance with the invention transmit a light level in the absence of supplied signal voltage.
  • the light transmission may be annoying in the spaces which are present between the conductive and the transparent electrodes. From this it follows that the parasitic average transmission level is added to the transmission levels which correspond to the effective values V O and V F of the applied signal, which results in a decrease of the displayed contrast.
  • an electrically insulating layer which absorbs the light, or a dielectric mirror is provided between the spaces.
  • the above-described devices are designed for operation with white light. It will be obvious that the light transmission can be better suppressed according as the wavelength range of the display light is smaller.
  • a filter is added to the input and to the output of said devices which passes only a part of the light spectrum.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Liquid Crystal (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
US06/047,393 1976-07-13 1979-06-11 Information display device having a liquid crystal cell Expired - Lifetime US4522468A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7621497A FR2358676A1 (fr) 1976-07-13 1976-07-13 Dispositif d'affichage d'information comportant une cellule de cristal liquide
FR7621497 1976-07-13

Related Parent Applications (1)

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US05812717 Continuation 1977-07-05

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US4522468A true US4522468A (en) 1985-06-11

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US06/047,393 Expired - Lifetime US4522468A (en) 1976-07-13 1979-06-11 Information display device having a liquid crystal cell

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US (1) US4522468A (OSRAM)
JP (1) JPS539552A (OSRAM)
CA (1) CA1086843A (OSRAM)
DE (1) DE2729972A1 (OSRAM)
FR (1) FR2358676A1 (OSRAM)
GB (1) GB1584822A (OSRAM)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4693562A (en) * 1984-12-07 1987-09-15 Hitachi, Ltd. Liquid crystal display device
US4708439A (en) * 1983-11-29 1987-11-24 Sharp Kabushiki Kaisha Liquid crystal display device with prism for viewing
US4877310A (en) * 1988-08-04 1989-10-31 Xerox Corporation Electronically variable MTF filter for image sensor arrays
US4884876A (en) * 1983-10-30 1989-12-05 Stereographics Corporation Achromatic liquid crystal shutter for stereoscopic and other applications
US4955816A (en) * 1989-04-20 1990-09-11 Molex Incorporated Electrical connector system and insulation displacement terminals therefor
US5119220A (en) * 1988-01-28 1992-06-02 Sanyo Electric Co., Ltd. Liquid crystal display device with a phase plate for shadow compensation
US5384650A (en) * 1992-04-06 1995-01-24 Hughes Aircraft Company Light valve with twisted perpendicular liquid crystal with a negative dielectric anisotropy
EP1054381A3 (en) * 1994-06-24 2001-08-22 Hitachi, Ltd. Active matrix liquid crystal display system of the horizontal field type with voltage for minimum brightness greater than zero, and driving method therefor

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SE425048B (sv) * 1978-04-24 1982-08-30 Ake Hornell Flerskiktsglas, serskilt skyddsglas i en svetsskerm
JPS6131947A (ja) * 1984-07-25 1986-02-14 Nippon Oil & Fats Co Ltd 自動凝固点測定装置
FR2568393B1 (fr) * 1984-07-26 1986-11-14 Commissariat Energie Atomique Cellule a cristal liquide nematique faiblement dope par un solute chiral, et du type a birefringence controlee electriquement
US4906073A (en) * 1987-07-29 1990-03-06 Hitachi, Ltd. Liquid crystal display device using nematic liquid crystal having twisted helical structure and a phase correction plate
JPH0260862U (OSRAM) * 1988-10-28 1990-05-07
DE3840797A1 (de) * 1988-12-01 1990-06-21 Licentia Gmbh Elektrooptische anordnung

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US4097128A (en) * 1975-04-24 1978-06-27 Tokyo Shibaura Electric Co., Ltd. Liquid crystal color display devices
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US4884876A (en) * 1983-10-30 1989-12-05 Stereographics Corporation Achromatic liquid crystal shutter for stereoscopic and other applications
US4708439A (en) * 1983-11-29 1987-11-24 Sharp Kabushiki Kaisha Liquid crystal display device with prism for viewing
US4693562A (en) * 1984-12-07 1987-09-15 Hitachi, Ltd. Liquid crystal display device
US5119220A (en) * 1988-01-28 1992-06-02 Sanyo Electric Co., Ltd. Liquid crystal display device with a phase plate for shadow compensation
US4877310A (en) * 1988-08-04 1989-10-31 Xerox Corporation Electronically variable MTF filter for image sensor arrays
US4955816A (en) * 1989-04-20 1990-09-11 Molex Incorporated Electrical connector system and insulation displacement terminals therefor
US5384650A (en) * 1992-04-06 1995-01-24 Hughes Aircraft Company Light valve with twisted perpendicular liquid crystal with a negative dielectric anisotropy
EP1054381A3 (en) * 1994-06-24 2001-08-22 Hitachi, Ltd. Active matrix liquid crystal display system of the horizontal field type with voltage for minimum brightness greater than zero, and driving method therefor

Also Published As

Publication number Publication date
CA1086843A (en) 1980-09-30
DE2729972A1 (de) 1978-01-19
GB1584822A (en) 1981-02-18
FR2358676B1 (OSRAM) 1979-07-06
JPS539552A (en) 1978-01-28
FR2358676A1 (fr) 1978-02-10

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